Now notice is put up in miniature (5)
I believe the answer is:
today
'now' is the definition.
(synonyms)
'notice is put up in miniature' is the wordplay.
'notice' becomes 'ad' (both can mean an advertisement).
'is put up' is a reversal indicator.
'in' is an insertion indicator.
'miniature' becomes 'toy' (synonyms).
'ad' backwards is 'da'.
'da' inserted into 'toy' is 'TODAY'.
(Other definitions for today that I've seen before include "one of our papers, once" , "Presently" , "At the present time, in general" , "Nowadays" , "Modern times" .)